Does "all" mean all the URLs publicly known, or did they exhaustively iterate the entire URL namespace?
How would that even function, I mean, did they loop through every single permutation and see the result, or what exactly/ how would that work?
In short, yes. Since no one can make new links, it's a pre-defined space to search. They just requested every possible key, and recorded the answer, and then uploaded it to a shared database.